Muzan x sister reader

Past

Onii -sama!

Onii-sama!

Onii-sama!

How could you do this to me?!?!

Muzan jerks up immediately. Cold sweat dripped down his face as he panted quickly. The cold night wind blowing through his window, hitting his pale skin, making him tremble from the cold.

"A. . .dream?" He mumbled confusedly as he placed a hand on his now hurting head. His throat was dry to the point that he wanted to go out and drink to the kitchen.

The pale boy grabs the bucket from the sink and cups his hands to gather water to drink. As the cold liquid runs down his dry throat, he sighed in relief.

As he stepped back, he was surprised to see his small sister on the doorway.

"Y/n? Didn't I tell you to stop sneaking on me?" He grumbled as he walked towards her small figure. Her lips formed in a frown as he stared at her red colored eyes.

A bright innocent smile appears on her face as she looked back at him. "But I didn't Muzan-nii. I was just watching you from afar" she argues, smiling at him.

The boy sighs and places his hand on her back, gently pushing her forward. "Go to bed. Okaasan and Otosan will get mad if you don't rest" he tells her as he walks her back to her room.

Y/n huffed, puffing out her cheeks. "Hmph! It's not like they'd notice" she groaned, crossing her arms as her feet stumbled every second.

Muzan his his frown, "I'll make them notice"

"Y/n? Are you ok?!" F/n asks as they both sat on the platform. The sun in high up in the sky.

Big elephant tears fell from the demoness's bright red eyes. It falls in the floor continuously as Y/n's hands trembled.

Her shaking hands raised to touch her face and feels the tears flowing down. "W-what?" She mumbled confusedly, her eyebrows burrowed as she grew confused.

"Hey. . . Are you-

-ok, Y/n?"

Y/n gasps as she hears Muzan's voice connecting with F/n. She holds her head as her brother's voice rumble inside her head. It echoes and continues on and on that she felt herself go crazy.

The memories that she had didn't want to remember coming back all at once. Her tears fell again as she now sobbed. Her nails digging into her scalp, making it bleed.

"N-no more Onii-sama! Please just let them b-be!" Y/n screams as she closed her eyes shut, her hair disheveled as she thrashed around.

"H-hey! Stop that!" F/n scolds as he tries to remove her grip from her head, only to grunt in frustration as he couldn't budge it.

"Onii-sama, can't we not do this? I mean. . .we're healed now right? Isn't that enough?-

"No it isn't. The fact that we have these powers is a sign that we must rule over"

"W-what? We can't do that!"

"Yes we can, Y/n. With your sly and manipulative mind and my brains and strength. . .we are an unstoppable force"

"I-I only wanted us to be happy! I d-didn't want t-this!" Y/n cried out as she held her head. The memories and emotions clashing together, confusing the demoness.

"Everything's a mess! Bring me back! It's so dark in here!"

"N-no! Onii-sama will get mad!" She shouts out of the blue, confusing her Kakushi male.